The purpose of this study is to analyze electrophysiological data obtained from heroin dependent individuals during acute withdrawal. The data collected in this study were from young healthy military personnel who were addicted to pure heroin, used almost no other drugs concurrently, utilized the naso-pulmonary route of administration and had short heroin use histories. This setting thus provided a good experimental model to evaluate heroin withdrawal without the many complications associated with stateside durg users. The physiological parameters obtained in this study included the electroencephalogram (EEG), electroculogram (EOG), electrocardiogram (EKG), electrophneumogram (EPG) and electrogastrogram (EGG). These data were from 20 patients and 5 drug-free controls and were collected on a 24-hour per day basis for 5-7 days. The EEG and EOG data will be scored into the standard awake and sleep states. Preliminary results indicate a disruption in the sleep-waking cycle during acute heroin withdrawal. Waking activity increased 18 percent during withdrawal, whereas sleep states (I-Iv) decreased 9 percent, 25 percent, 23 percent, and 38 percent for states I, II III and IV, respectivley, with REM sleep showing the largest decrease of almost 69 percent. Analysis of these data is important in the understanding of drug dependence and withdrawal and may improve the prognosis for opiate dependent individuals.